AIS Data Irregularity

Report Text:

V/l coming up from SW, passing clear and no problem to us but AIS indicating deficient information as Static Ship & Voyage Data Missing, hence no ship name or call sign indicated. The SOG, COG and HDG data were all correct. I know there is an M Notice about poor AIS data to send to nearest MRCC but unable to get through on fax to local MRCC. Appears AIS not set up properly. A pity because it is an excellent tool.

CHIRP Comment:

The UK M Notice referred to is MIN 231. Although the notice expired on 01 April 2007 it is still available and contains a reporting format and some useful information:

“The MCA, as the UK Competent Authority, has received reports of vessels transmitting incorrect AIS data.  This can be a danger to navigation and weakens confidence in the system.

The errors reported include:

  • dynamic data (especially heading errors)
  • operator input fields and
  • predefined fields.

Causes can be:

  • faulty interfaces, particularly with the gyro compass,
  • incorrectly entered Maritime Mobile Service Identities (MMSI) or International Maritime Organization (IMO) numbers,
  • incorrect Destination and estimated time of arrival (ETA) and failure to change vessel status or the use of an incorrect vessel status.”

A number of reports similar to this one have been received.  This report was forwarded to the vessel’s operator, who responded as follows:

“We requested the vessel to test the AIS and received the reply below.

Furthermore we have now instructed all vessels to reset their AIS units at the beginning of each watch.

This has been a help in improving our Safety on board



Fm: Master

Your msg well received.

I checked AIS and on display have been shown all information including ship’s name and call sign.

For confirmation proper transmission I called vessel which was 3 Nm from us. This vessel was receiving all our data except ship’s name and call sign. Due to a/m I reset our AIS unit and after that the vessel by side of us has confirmed receiving all data also with ship’s name and call sign.

I don’t know what is the reason that on display is shown all data and we are not transmitting same but we will look for it.

To avoid such situation in future I ordered as routine to reset AIS unit on beginning of every watch.”

The Board is grateful for this response and in addition suggests it is important to notify manufacturers of such incidents so that equipment performance and reliability may be improved.